I literally said it has nothing to do with Photoshop - if you shoot a photo on your iPhone or Google Pixel it shoots in HDR, and then you just use the built-in editor on your PHONE, it will edit in HDR. Linux is worse than Pixel and iOS stock photo apps at photo editing. I don’t know why you’re obsessed with Photoshop.
The logic was just that when UNIX was originally evolving, they ran out of disk space on their PDP-11 and had to start moving less-essential binaries to a different disk. That’s why it’s “/usr/” which was originally for user data but that disk happened to have free space.
Any other explanation is just retcon. Some distros try to simplify things.